Abstract 258P
Background
TNT has recently changed treatment strategy of LARC thanks to increased clinical and pathological complete responses (cCR and pCR) and the possibility of avoiding major surgery by adopting a watch and wait (W-W) approach in case of cCR. The aim of this study is to evaluate in a real word retrospective analysis the applicability of TNT and its implications.
Methods
In 6 centers we evaluated 185 LARC microsatellite stables patients (pts), M/F=107/78, with a median distance from anal verge 5-7 cm. 27 pts classified as cT3N0/c(any)TN+, underwent surgery followed by RT/CHT. The other 158 pts were treated with a neoadjuvant approach: 97 pts (62%) with standard RT/CHT (group A) and 61 pts (38%) with TNT (group B). Pts with bulky disease cT4N+ were 33% group B and 9% group A. Group B chemotherapy was FOLFOX/XELOX (55%) and FOLFOXIRI (45%).
Results
Surgery was performed in 124 pts, 84 pts (86%) group A and 40 pts (65%) group B (p=0.015), with 12% transanal resection in group B and 0% in group A. pCR in group A was 18% (radiological cCR 40% and near cCR/cRP 60%) vs 28% in group B (radiological cCR 45%, near cCR/cPR 36%, cSD 18%). In pts not achieving a pCR, radiological cCR was 10%. W-W was offered to 4 pts (4%) group A and 10 pts (16%) group B who had cCR/near cCR: 1 pt in group B recurred after 1y and was treated with surgery. Overall, the 2y-DFS was 75,3% and the 5y-DFS 51,9%. In pts with upfront surgery 2y-DFS was 78,1% and 5y-DFS 71%, in pts treated with neoadjuvant therapy 2y-DFS was 73,9% and 5y-DFS 45,1%, probably because of more advanced disease. In neoadjuvant pts, 2y-DFS was 76,5% in group A vs 70,2% in group B and 5y-DFS was 52,7% vs 23,9%, respectively(p=0.043). In pts with bulky cT4N+, 5y-DFS was 24,7% in group B and 0% in group A, confirming long-term disease control in TNT. In the general population 2y-OS was 92,5% and 5y-OS 80%. For surgery upfront 2y-OS was 84,8% and 5y-OS 77,8%, in neoadjuvant pts 2y-OS 93,2% and 5y-OS 84,2% (numerically superior OS but p value not significant).
Conclusions
In our neoadjuvant population, TNT confirmed an increase in pCR but also in radiological major response. This encourages conservative transanal surgery or W-W when a multidisciplinary approach is strictly applied. This strategy needs to be further implemented.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.